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6TJOH0CTFSWBUJPO

6TJOH!0CTFSWBCMF 6TJOH0CTFSWBUJPO @Observable class FoodTruckModel { var orders: [Order] = [] var donuts = Donut.all }

6TJOH!0CTFSWBCMF 6TJOH0CTFSWBUJPO @Observable class FoodTruckModel { var orders: [Order] = [] var donuts = Donut.all } Ξϊςʔγϣϯ͸ҰՕॴ શϓϩύςΟ͕τϥοΩϯάͰ͖Δ

&YQBOE.BDSP 6TJOH0CTFSWBUJPO @Observable class FoodTruckModel { @ObservationTracked var orders: [Order] = [] @ObservationTracked var donuts = Donut.all @ObservationIgnored private let _$observationRegistrar = ObservationRegistrar() internal nonisolated func access( keyPath: KeyPath ) { _$observationRegistrar.access(self, keyPath: keyPath) } internal nonisolated func withMutation( keyPath: KeyPath, _ mutation: () throws -> T ) rethrows -> T { try _$observationRegistrar.withMutation(of: self, keyPath: keyPath, mutation) } @ObservationIgnored private var _orders: [Order] = [] @ObservationIgnored private var _donuts = Donut.all } extension FoodTruckModel : Observable {}

4XJGU6*QSPQFSUZUSBDLJOH 6TJOH0CTFSWBUJPO @Observable class FoodTruckModel { var orders: [Order] = [] var donuts = Donut.all } struct DonutMenu: View { let model: FoodTruckModel var body: some View { List { Section("Donuts") { ForEach(model.donuts) { donut in Text(donut.name) } Button("Add new donut") { model.addDonut() } } } } }

4XJGU6*QSPQFSUZUSBDLJOH 6TJOH0CTFSWBUJPO @Observable class FoodTruckModel { var orders: [Order] = [] var donuts = Donut.all } struct DonutMenu: View { let model: FoodTruckModel var body: some View { List { Section("Donuts") { ForEach(model.donuts) { donut in Text(donut.name) } Button("Add new donut") { model.addDonut() } } } } } Ξϊςʔγϣϯ͕ෆཁ

6TJOH1SPQFSUZ8SBQQFS

6TJOH!4UBUF 6TJOH1SPQFSUZ8SBQQFS struct DonutListView: View { var donutList: DonutList @State private var donutToAdd: Donut? var body: some View { List(donutList.donuts) { DonutView(donut: $0) } Button("Add Donut") { donutToAdd = Donut() } .sheet(item: $donutToAdd) { TextField("Name", text: $donutToAdd.name) Button("Save") { donutList.donuts.append(donutToAdd) donutToAdd = nil } Button("Cancel") { donutToAdd = nil } } } }

6TJOH!&OWJSPONFOU 6TJOH1SPQFSUZ8SBQQFS @Observable class Account { var userName: String? } struct FoodTruckMenuView : View { @Environment(Account.self) var account var body: some View { if let name = account.userName { HStack { Text(name); Button("Log out") { account.logOut() } } } else { Button("Login") { account.showLogin() } } } }

6TJOH!#JOEBCMF 6TJOH1SPQFSUZ8SBQQFS @Observable class Donut { var name: String } struct DonutView: View { @Bindable var donut: Donut var body: some View { TextField("Name", text: $donut.name) } }

4UPSJOH!0CTFSWBCMFUZQFTJO"SSBZ 6TJOH1SPQFSUZ8SBQQFS @Observable class Donut { var name: String } struct DonutList: View { var donuts: [Donut] var body: some View { List(donuts) { donut in HStack { Text(donut.name) Spacer() Button("Randomize") { donut.name = randomName() } } } } }

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